Colin Powell was fully vaccinated, but he still died from COVID complications. How rare is that?

Many Americans were shocked to learn of Colin Powell’s death from COVID-19-related complications Monday, especially because the former secretary of state and retired four-star general was fully vaccinated against the disease.

“We have lost a remarkable and loving husband, father, grandfather and a great Americans,” Powell’s family said in its statement.

Although dying from COVID-19 is extremely uncommon among the fully vaccinated, health experts say age and preexisting medical conditions may increase the odds of breakthrough infection, severe disease and even death.

Newly released data from the Centers for Disease Control and Prevention shows fully vaccinated people 80 and older are about as likely to die from a COVID-19 infection as unvaccinated people in their 50s and early 60s.  

The CDC also reports that as of Oct. 12, 7,178 deaths among vaccinated people; 85% of the deaths are in people 65 and older.

At 84, health experts say, Powell fell into this high-risk group.

“As we get older, our immune system is weaker and it is less likely to respond appropriately to vaccinations, and we’re more likely to get ill when we do get exposed to infection,” said Dr. Kristin Englund, an infectious disease expert at the Cleveland Clinic. “That’s why very early on we targeted vaccines for our elderly population.”

Because older people were some of the first Americans to get vaccinated, she said, it’s possible Powell’s immunity may have waned over time, although it’s not clear exactly when he got his first shot.

Research suggests that may be happening among other populations, too. A study in August from the CDC showed vaccine effectiveness decreased among health care workers who were fully vaccinated since the time the delta coronavirus variant became widespread. 

But the odds of dying are still much worse if the person is unvaccinated. Unvaccinated people 80 and older are about six times more likely to die from a COVID-19 infection than vaccinated people in the same age group, CDC data shows.

Powell may have also had multiple myeloma, according to media reports, which is a type of blood cancer that affects the body’s immune system. Health experts say that undoubtedly would have played a role in his ability to fight off infection.

“He had a cancer of his white blood cells, and those are the some of the cells that we need to help fight infections,” Englund said. “Typically it affects the B-cells in the white blood cells that help us form antibodies and immunity.”

Myeloma is more commonly seen in people over 60, said Dr. Don Benson, hematologist-oncologist at The Ohio State University Comprehensive Cancer Center.

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Roughly 35,000 cases of myeloma are reported in the U.S. each year. Although it’s considered an incurable cancer, most patients don’t die from the disease itself.

“Far and away the most common cause of death is actually infection,” Benson said. “Both the disease and the treatments that we use will either suppress or dysregulate their immune function and make them more susceptible to not just COVID but bacterial and other viral infections.” 

To better protect vulnerable populations, the Food and Drug Administration authorized a third COVID-19 vaccine shot in August for people with severely weakened immune systems.

That made roughly 2.7 million immunocompromised Americans eligible to receive a third shot of the Pfizer-BioNTech vaccine, including those who are in cancer treatment, received organ transplants or are taking immunosuppressive therapy. 

The agency also authorized a booster shot of the Pfizer vaccine in September for people 65 and older, younger adults with underlying health conditions and those in jobs that put them at high risk for infection. More than 8.8 million people have received a Pfizer booster since its authorization.

Last week, an FDA advisory committee voted to support a half-dose booster shot of the Moderna vaccine for similar populations. The panel also decided Friday that the Johnson & Johnson vaccine should be considered a two-dose vaccine rather than the one-and-done shot that had received initial authorization.

Powell’s family did not say whether he received a third shot. But Englund said it’s difficult to speculate whether it would have prevented infection.

“He had a very difficult blood cancer that he has been fighting. Whether he would have had an adequate response to a booster is unclear,” she said. “We don’t know his status of multiple myeloma, and we don’t know if a booster would have helped him.”

What would have helped, Englund said, is if more Americans were fully vaccinated. Powell’s death is an important reminder to get vaccinated, not only to protect yourself, but also to protect vulnerable populations such as the elderly and those with immunocompromising conditions, she said.

“If we could all do our part like he did throughout his entire life to serve Americans and get vaccinated, then maybe we could have built a ring of protection around him so he would have never been exposed to COVID,” she said. “He served his country the best he could, and now it’s our duty to do the same.”

Contributing: Mike Stucka, USA TODAY. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.